Mark the correct alternative in the following:

The number of different ways in which 8 persons can stand in a row so that between two particular persons A and B there are always two persons, is


As, it is required that, two particular persons A and B there are always two persons so, let us consider this arrangement be “A××B” and consider it as a single object.


So, we are left with, 4 persons and an object, i.e. total 5 objects.


Now, this 5 objects can be arranged in 5! ways.


Again, the two ‘×’ are to be filled with 2 persons from 6 persons, this can be done in 6P2 = 30 ways.


Two persons ‘A’ and ‘B’ can be arranged in 2! = 2 ways.


So, the total number of different ways in which 8 persons can stand in a row so that between two particular persons A and B there are always two persons, is


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